The HX Files 020
Hello and welcome to the X cert 20 of the HX Files.
In this months Echo Ireland I would like to talk about a
permanent /m ATV unit.
Although having
made a portable/mobile unit a few months ago, thoughts of that it might be very
handy to have an ATV station semi-permanently setup in the car came to mind,
the system could be left in the car but would be removed if the weather should
turn frosty for a protracted time and that may cause all the smoke to get out if
it was left unused in the winter time and woken up in our summer (around 2
weeks in May).
This transceiver would have to be safe to use with very
little having to be manually adjusted and using as many parts that have an auto
function option. As it is illegal to have a mobile/cell phone in your hand
whilst driving the chances of time in the slammer would be a sure thing if you
had a camcorder, lights and clapper board in your hands, it would be literally
a case of car crash TV for sure. The first job before even starting to build
the transceiver would be the location of the cameras and what type to use,
obviously the smaller the better as you would not them to interfere with you
seeing were you were going, luckily thanks to the parts department the cameras
were found that were needed.
In photo 1on the left, you can see the cameras that would be
used in the project. The locations of the cameras would be dictated by the safe
routing of the audio, video and DC cables, only one of the cameras was capable
of sound (the camera on the left in photo 1) and its audio line would be
connected straight to the transmitter, and that would mean that it didn't matter what camera was in use as the audio would always be inline. The
camera that had sound would be mounted on the front pillar, and the second
camera would be mounted in the centre of the dashboard as there was a switch
blanking plate as the model of my car had not got a particular optional accessory
fitted (ejector seat), so removing the blanking plate exposed an opening that
was a perfect fit for that camera, the camera had its own mounting bracket and
some of it was used in the cameras installation the most awkward part of that job was making sure that the
cables were well away from the adjustment leavers for the air vents. Next jobs
to plan were the type of enclosure to use for the transceiver be it either a metal
or plastic, and whether to place the transceiver inside the car or on the
outside. The size of the box that was to be used was a bit to big to install in
the car when you think of were all the cables had to be routed, and were it
would not get in the way of operating the car, or any passenger, so outside it
was to be, but were to place it, on the bonnet making it look like an air intake
for the supercharger, or painting it blue and placing it on the roof, so under
the boot but bear the bumper it was to
be, I had to make sure that the box and
the cables were not visible by people from under the car, as they may think
that a box and cables hanging from under a car is something other than an ATV transceiver,(unless
they were my neighbours, as they would be use to seeing strange things sticking
out of my car, and they would be more likely to phone the home for the bewildered and put Pat out of his misery). As my car has
a tow bar fitted and also has some other factory fitted threaded holes for
various other fittings including of course the fact that it is available in left
hand drive for other markets, there would be plenty of places to secure the unit but making sure that it had plenty of
cooling air passing over it. The aerial, an Alford Slot, would not be
permanently mounted on the car so I would be using some good coaxial cable ( Aercil 9) but as short as possible, and I would be using some quick form of
lock / unlock poles and they and the aerial would be left in the car when not
in use. Something else to consider was the monitor I would use to watch the
received signals when I parked.
Having chosen the
metal box the first thing done was to see what type of brackets would have to
be made to attach the unit to the car, once the brackets were fitted to the box
it was coated inside and out, and this would protect it as the box was one of
the die cast aluminium type, and those that have used them without any
protective covering would know that in our climate they could get a bit of a
dusty coating inside and out, and without that protective coating the
conductive dust that formed would / could fall from the inside and possibly short
out the transceiver and let all the smoke out. So after having let the coating
harden for a few days, I covered it with some masking tape so it could be mark
out were I was to drill and also to protect the painted finish as I could
repaint any bare metal that there was after the drilling, cutting and filing.
After laying out the parts (most can be seen in photo 3 below)
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| Top left RX, Top right TX Bottom left, fan mounted on heat sink, Bottom right amp mounted to heat sink |
to see what went were
for the best placement of the parts being used, the first thing done was to put
the amp on the side that would have the most air passing over it and then a
hole slightly smaller than the fan would be cut out of the project box. Not
wanting to just rely on the box as a heat sink, the amp would have its own
fitted, so when I would be parked the transceiver would not get to hot, and also,
fitting a cooling fan that would not mind getting a few splashes from the
puddles that would be driven through, so using a heat sink and attaching it to
the amp and then being placed close to the drilled hole in the project box and
the fan in it also, it will be running cool. When the final place for the unit
was chosen some time was spent on seeing how to run the various cables to it
and how to gain access to the car from the underneath and not let anything in
like water or exhaust gases. So bringing the cable in through the boot of the
car, and the under the rear seats up to the front seats, at that end of the
cable it was terminated into a box, that box would be fed with the DC cable and
the Audio/Video from the camera in use via a switching unit (photo 4 on the left),
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| Video switching unit |
also the
box would have cables for the received Audio and Video. The monitor to be used
would have to be a small one and the one I had in mind was a 100mm and it could
be easily stored when not in use in the glove box as I would not be receiving
signals while mobile as that would not be safe or legal. As the amp and other
parts would use around 8 amps, and deciding splicing into the rear wiring loom
would not be an option as the loom would not be able to handle that current and
I did not like the idea of a permanently live cable running the full length of
the car even fitted with fuses from the battery carrying high amps, so I had a
smaller lead from the battery to a connector that would plug into the main termination
box that was fitted inside a storage bin
in the car for music cassettes,( remember them, and the 8-track tapes) and when it was needed the two
ends were connected, a switch on the rear end of the lead was fitted to power on and off the transceiver. Not wanting
to be adjusting anything whilst driving, sometime was spent initially setting
up the cameras as I would not be able to do any adjustments whilst driving, and
using a 50mw transmitter at first was able to monitor the signal myself as well
as sending a signal to Tony EI 4 DIB who could give a live report on the picture from the cameras and the
sound via 2mts , Tony was also able to help fine tune the audio when I used the
full mobile setup on the road as having
another pair of ears and eyes would save me a lot time later on by doing all the major adjustments now and not
after a number of QSO’s, a few tests were also done with the aide of Derek EI 7 CHB from Skerries, in this test I was using
an infrared camera (on the right in photo 1) as this test was at night for a
different view, and as before the infrared
camera was bolted to the towing eye on the front of the car. With all
the tests done and the transceiver bolted in place I will be using it when I am
visiting the local Hams and SWL’ers that have an ATV setup.
As you can see from
photo 2 on the left, there is not a lot to see from the outside of the car, and I do not
know if I will be 10GHz mobile much of the time, as the dishes I have at the
moment are all the solid type and that would cause some drag a when in use as
it would catch some air, also a Horn type aerial would do the same.
Anyway off to the
funny farm with me for some shock therapy, but before I go, I would like to
again thank Tony and Derek, for helping with the trials and testing and Anthony
EI 2 KC for taking some of the photos.please note the other photos at the bottom of the page also.May all your signals be P5.
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| On the way |
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| Pillar camera |
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| On the way 2 |
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| Dash camera |
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| On air |
